I'm seeing the same issue on a Dell XPS 9560, which is basically the same laptop as the Precision 5520 with a different GPU.
[ 335.012863] pcieport 0000:00:1d.0: AER: Corrected error received: 0000:04:00.0 [ 335.012869] nvme 0000:04:00.0: AER: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID) [ 335.012871] nvme 0000:04:00.0: AER: device [144d:a804] error status/mask=00000001/00006000 [ 335.012873] nvme 0000:04:00.0: AER: [ 0] RxErr
Linux OrionXPS 5.3.0-26-generic #28~18.04.1-Ubuntu SMP Wed Dec 18 16:40:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
I'm seeing the same issue on a Dell XPS 9560, which is basically the same laptop as the Precision 5520 with a different GPU.
[ 335.012863] pcieport 0000:00:1d.0: AER: Corrected error received: 0000:04:00.0 mask=00000001/ 00006000
[ 335.012869] nvme 0000:04:00.0: AER: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[ 335.012871] nvme 0000:04:00.0: AER: device [144d:a804] error status/
[ 335.012873] nvme 0000:04:00.0: AER: [ 0] RxErr
Linux OrionXPS 5.3.0-26-generic #28~18.04.1-Ubuntu SMP Wed Dec 18 16:40:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux